11-Rock Drop Structure-Pdf

1/3 X4 X1 - ROCK DROP STRUCTURE INVERT CONTROL

TOP OF BANK, TYPICAL POINT ELEVATION, TYPICAL (SEE NOTE 2) FLOW

X3 - RIGHT VANE ARM INTERCEPT CONTROL POINT ELEVATION, CONNECTING BOULDER, TYPICAL TYPICAL (SEE NOTE 2) (SEE NOTE 9)

SCOUR POOL, TYPICAL

A A'

FLOODPLAIN SILL, PHOTO: ROCK DROP STRUCTURE AT PIPE OUTLET TYPICAL X9

FILTER FABRIC X16 (SEE NOTE 7)

TOP OF BANK X4

X7 X17 1/3 X4 1 X10 X12

COARSE BACKFILL

(SEE NOTE 8) FLOW

X2 - LEFT VANE ARM INTERCEPT X2 - LEFT VANE ARM INTERCEPT X4 CONTROL POINT ELEVATION, CONTROL POINT ELEVATION X16 TYPICAL (SEE NOTE 2) FOOTER BOULDER, TYPICAL (SEE NOTE 6)

X8 HEADER BOULDER, TYPICAL (SEE NOTE 6)

PLAN VIEW X3 - RIGHT VANE ARM INTERCEPT X1 - ROCK DROP STRUCTURE INVERT CONTROL POINT ELEVATION CROSS SECTION A - A' CONTROL POINT ELEVATION

THIS FIGURE IS ONLY MEANT TO DEFINE THE MINIMUM INFORMATION REQUIRED BY THE CITY OF CHARLOTTE TO BE INCLUDED IN A DETAIL FOR THIS TYPE OF TECHNIQUE. THIS FIGURE IS NOT MEANT TO REPRESENT A STANDARD DESIGN METHOD FOR THIS TYPE OF TECHNIQUE AND SHALL NOT BE USED AS SUCH. NOT TO SCALE SHEET NUMBER ROCK DROP STRUCTURE 1 OF 2 REV. DATE REV. # DRAFT - NOT TO BE USED FOR CONSTRUCTION NOTES: X7 1. A ROCK DROP STRUCTURE IS A SERIES OF TWO OR MORE INTERCONNECTED IN-STREAM, GRADE CONTROL STRUCTURES THAT DIRECT STREAM FLOW AWAY FROM THE STREAM BANKS AND IN TOWARD TOP OF BANK THE CENTER OF THE CHANNEL. THESE STRUCTURES SHALL TYPICALLY BE USED TO TIE-IN STORM DRAINAGE PIPES AND CHANNELS TO STREAMS ON STEEP SLOPES. FISH PASSAGE IS NOT A CONCERN. FILTER FABRIC IF FISH PASSAGE IS A CONCERN HOWEVER, THE DROPS BETWEEN EACH STRUCTURE SHALL BE LIMITED FLOW AS SPECIFIED BY THE DESIGNER. HEADER BOULDER,TYPICAL 2. ELEVATION CONTROL POINTS SHALL BE DESIGNATED THE UPSTREAM INVERT OF EACH GRADE X1 - ROCK DROP STRUCTURE X11 CONTROL STRUCTURE TO ESTABLISH PART OF THE PROFILE. SURVEY OF CONTROL POINTS SHALL BE INVERT CONTROL POINT REQUIRED TO ESTABLISH ACCURATE ROCK DROP STRUCTURE INSTALLATION WITHIN THE TOLERANCE ELEVATION, TYPICAL SPECIFIED BY THE DESIGNER. X10 (SEE NOTE 2) 3. EACH VANE ARM SHALL RISE FROM THE INVERT TO INTERCEPT THE STREAM BANK AT A HEIGHT EQUAL TO BETWEEN ½ BANKFULL STAGE AND BANKFULL STAGE. ELEVATION CONTROL POINTS MAY BE FOOTER BOULDER,TYPICAL ESTABLISHED AT THE LEFT AND RIGHT STREAM BANK/VANE ARM INTERCEPT POINTS. BANKFULL IS NOT PROFILE NECESSARILY THE TOP OF THE STREAM BANK SLOPE. 4. A TABLE OF ALL STATION LOCATIONS AND CONTROL POINT ELEVATIONS OF THE ROCK DROP STRUCTURE SHALL BE PROVIDED IN THIS DETAIL. DIMENSIONS (VALUES TO BE PROVIDED BY DESIGNER) 5. A TYPICAL CROSS SECTION SHALL BE PROVIDED ELSEWHERE IN THE PLANS TO ESTABLISH THE VARIABLE VALUES TYPICAL UNIT DESCRIPTION DIMENSIONS OF THE CHANNEL GRADING INTO WHICH THE ROCK DROP STRUCTURE IS TO BE INSTALLED. X1 FT. (NAVD) INVERT CONTROL POINT ELEVATION 6. THE ROCK DROP STRUCTURES SHALL BE CONSTRUCTED WITH FLAT-SIDED BOULDERS OF A SIZE X2 FT. (NAVD) LEFT INTERCEPT CONTROL POINT ELEVATION (LENGTH, WIDTH, AND DEPTH) AS SPECIFIED BY THE DESIGNER.

X3 FT. (NAVD) RIGHT INTERCEPT CONTROL POINT ELEVATION 7. FILTER FABRIC OF A TYPE AND SIZE SPECIFIED BY THE DESIGNER SHALL BE USED TO SEAL THE GAPS BETWEEN THE BOULDERS AND UNDER THE COARSE BACKFILL MATERIAL.

X4 FT. BANKFULL WIDTH 8. COARSE BACKFILL OF THE ROCK DROP STRUCTURE SHALL BE OF A TYPE, SIZE, AND GRADATION AS SPECIFIED BY THE DESIGNER. COARSE BACKFILL SHALL BE PLACED IN EACH GRADE CONTROL X5 IN. OR FT. D50 OF COARSE BACKFILL STRUCTURE TO A THICKNESS EQUAL TO THE DEPTH OF THE HEADER AND FOOTER BOULDERS AND SHALL ALSO EXTEND OUT FROM THE VANE ARMS TO THE STREAM BANK. X6 FT. VANE ARM LENGTH 9. THE INVERT (CENTER) OF EACH GRADE CONTROL STRUCTURE SHALL BE CONSTRUCTED FIRST, X7 FT. LENGTH OF INDIVIDUAL GRADE CONTROL STRUCTURE FOLLOWED BY ONE VANE ARM AND THEN THE OTHER VANE ARM. BOULDERS CONNECTING THE INDIVIDUAL GRADE CONTROL STRUCTURES SHALL THEN BE INSTALLED. THE FLOODPLAIN SILLS SHALL X8 FT. LENGTH OF FLOODPLAIN SILL BE CONSTRUCTED LAST AND ARE REQUIRED ON AT LEAST THE FIRST AND LAST OF THE INTERCONNECTED GRADE CONTROL STRUCTURES. X9 DEGREES VANE ARM ANGLE WITH TOP OF BANK 10. ROCK DROP STRUCTURES SHALL BE BUILT TYPICALLY AS FOLLOWS: DIFFERENCE BETWEEN TOP OF BANK AND VANE ARM INTERCEPT X10 IN. OR FT. POINT A. BEGIN WITH THE DOWNSTREAM-MOST (LOWEST) GRADE CONTROL STRUCTURE. B. OVER-EXCAVATE STREAM BED TO A DEPTH EQUAL TO THE TOTAL THICKNESS OF THE HEADER X11 IN. OR FT. DROP BETWEEN INVERTS AND FOOTER BOULDERS. C. PLACE FOOTER BOULDERS. THERE SHALL BE NO GAPS BETWEEN BOULDERS. X12 PERCENT VANE ARM SLOPE D. INSTALL FILTER FABRIC. E. PLACE COURSE BACKFILL BEHIND THE FOOTER BOULDERS. X13 IN. OR FT. BOULDER LENGTH F. INSTALL HEADER BOULDERS ON TOP OF AND SET SLIGHTLY BACK FROM THE FOOTER BOULDERS (SUCH THAT PART OF THE HEADER BOULDER IS RESTING ON THE COARSE BACKFILL). HEADER BOULDERS SHALL SPAN THE SEAMS OF THE FOOTER BOULDERS. THERE X14 IN. OR FT. BOULDER WIDTH SHALL BE NO GAPS BETWEEN BOULDERS. G. PLACE COARSE BACKFILL BEHIND HEADER BOULDERS ENSURING THAT ANY VOIDS BETWEEN X15 IN. OR FT. BOULDER THICKNESS THE BOULDERS ARE FILLED.

X16 FT. CHANNEL WIDTH 11. IF ANY EROSION CONTROL MATTING IS SPECIFIED FOR USE IN THE VICINITY OF THE VANE ARM INTERCEPT POINTS AND FLOODPLAIN SILLS ALL MATTING EDGES SHALL BE NEATLY SECURED AROUND X17 NONE BANK SLOPE RATIO (HORIZONTAL COMPONENT) THE BOULDERS.